Unless you force it otherwise, *buntu always installs Grub to the MBR
only, which for most *buntu installs means there is no Grub2 on its /
partition, and thus chainloading to it won't do anything.

You'll need to create a full stanza in openSUSE's menu.lst to load
*buntu's kernel and initrd just as if it was loading an openSUSE
kernel/initrd. Just follow the pattern used for the openSUSE kernels,
but adjust the actual kernel name to what actually exists, initrd
name, (disk/partition) numbers, and root=[device name,partition
label,UUID,deviceID] for its / partition and give that a try. If it
fails likely there's some additional cmdline argument you'll have to
dig out of /boot/grub/grub.cfg stanzas on the *buntu / partition.

Once you manage to get *buntu to boot the first time, sometime before
doing any updates on it, you'll need to reconfigure it to install
Grub2 to only its / partition, in part so that updates won't foul your
openSUSE boot configuration, and other part so it's own bootloader
config can be functionally kept up to date when its new kernels are
installed and initrds updated.

Don't forget, menu.lst is just a form of scripting. Once you
understand the meaning of the contents of menu.lst, you can use that
knowledge to do anything required to get any partition to boot using
the Grub shell instead of menu.lst. IOW, without any advance planning
or config file editing, you could exit the openSUSE Grub menu
immediately to the Grub shell, locate *buntu's kernel and initrd, load
them, and boot *buntu.
http://www.gnu.org/software/grub/manual/legacy/grub.html

Felix, Billie has already stated that he is no guru - and all he ever
wants now is to simply install a system and *use* it rather than go
around fart-arsing around with it.

I suggest that you give Billie a clearly written out menu.lst, for
example, with which he can replace his current one but *after* he makes
a copy of his current one to fall-back on if things go belly up.